[v12-engine] engine oil

V12-Engine
21

It is all good and well reading a pressure gauge, but it doesn’t tell the
whole story. Another important factor is oil temperature.

I don’t have an oil temp gauge installed in the Daimler, but my other car
has one, and it is quite amazing to see the running temp differences between
various oils of the same viscosity ranges.

The needle staying at 50 is nice, but it does nothing good for your engine
if the oil stays too cold and thus too thick.

If you drive the engine really hard, an oil temp gauge is an essential
instrument.

Just my 2 cts,

Jack Verschuur

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22

In reply to a message from The Wirewheel Shop sent Wed 10 Oct 2007:

Here are some responses to this thread to this point.

For interesting information only. Mobil 1 was introduced into
aviation for the air cooled engines. I think it was the first full
synthetic to receive an FAA PMA required for aviation products,
with some exceptions.

An organization or group in the NW area north of Seattle started a
class action suit against Mobil 1 for various engine problems
leading to an abnormally short life of the engine or some of its
parts. Mobil 1 was withdrawn from the aviation use about 15 years
ago. Maybe it’s back, but I doubt it.

As far as oil sticking to parts, and especially cams. The Lycoming
cam will start to rust in a few days! In fairness the cam is
situated on top of the rotating parts of the engine and may receive
moisture from the oil during cooldown. This rust, when light, may
pose no problem. Frequent usage engines last longer, ie: accrue
more hours before overhaul or failure. However, engines that sit
for longer periods develope rust pits, however small, and this
starts the cam in a spiral of wear until the engine needs cam
associated maintenance. I believe the term is Brinnelling or
spalling of the surfaces as the rust pits cause the surface to
break out little hardened bits of cam or tappets.
To assist the drainback issue on these engines, some owners have
adopted a proceedure of letting the engine cool down and then
restarting it, briefly, to get thick oil back on the interior
surfaces.

As Jack states, Oil temperature is very important. Referring to
aviation again, The maximum inlet temperature of the engine oil is
REDLINED at 245 degrees F. The desired oil temp is regarded as 185
degrees F.

For most of us around 240 degrees may be the radiator water temp on
a hot day.

Do you think the oil in an engine using relief oil bypassing, where
the oil is not ported to pass through the oil cooler when the oil
is really hot and the pressure gauge shows less than the normal
pressure, has a chance of being below 245 degrees??? What
percentage of the heat is removed by the oil? Where does it go?

PLEASE, somebody with oil knowlege step in here and tell us what
our engines are experiencing.

Regards, Noel

A very important technical thread going here!–
The original message included these comments:

It is all good and well reading a pressure gauge, but it doesn’t tell the
whole story. Another important factor is oil temperature.
has one, and it is quite amazing to see the running temp differences between
various oils of the same viscosity ranges.
if the oil stays too cold and thus too thick.
If you drive the engine really hard, an oil temp gauge is an essential
instrument.

–
'92 XJS Conv, '88 XJS Coupe, 1914 &1915 Ford T’s (Forguars)
Edmond, OK, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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23

Do you think the oil in an engine using relief oil bypassing, where
the oil is not ported to pass through the oil cooler when the oil
is really hot and the pressure gauge shows less than the normal
pressure, has a chance of being below 245 degrees??? What
percentage of the heat is removed by the oil? Where does it go?

PLEASE, somebody with oil knowlege step in here and tell us what
our engines are experiencing.

Regards, Noel-------------------------------------------------------------------------

I made up spare temperature sensors for the HE engine now sitting in
the pre HE car.
These are small AD590 silicon sensors, an electronics industry
standard for over 20 years now and much better than thermistors.
They are epoxied into a piece of hex brass bar which has a thread at
one end to suit the myriad different threads needed to service a British car.
The other end has a socket to suit the 2 pin plugs similar to the
injector plugs.

There is provision to measure 6 points with a digital readout in the
driver side ashtray.

For the last 10 years while driving the pre HE with an aftermarket EFI
it has been possible to log temperatures on the A and B bank water
rail plus 4 other items.
My guess is I could drill a hole in one of the oil gallery blanking
plugs on the HE block and insert a temperature sensor. The idea would
be not to break through the plug, just bottom the drill 3mm from the
plug end. That would give oil temperature in the gallery which is the
place where it counts.
It might not be exact temperature of oil, depending on the temperature
of the plug, but it will be within 5 deg C.

In fact it would be better to use the hex brass bar to make the sensor
housing. I will check if I have a die to cut the thread, which I
think is either 1/2" or 7/16" UNC.

That will give an answer, at least for my engine which is basically
standard except for electric coolant pump.

Richard Dowling, Melbourne, Australia.
1979 XJ-S V12 coupe, 1988 XJ-S V12 convertible, 1985 XJ6.

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